The present invention relates to a motor vehicle having a body and a bonnet of which a first edge thereof is adapted to be raised from a rest position into a limit position by an actuator that is supported on the body and a second edge thereof is supported on the body.
Increased legal requirements in regard to the protection of pedestrians in the event of accidents demand better accident prevention properties from modern motor vehicles. In order to decrease the consequences for a pedestrian and protect the pedestrian from severe injuries in the event of an impact especially of the pedestrian's head on the bonnet, it is desirable that the pedestrian or his head be slowed down as gradually as possible, for instance, by a deformation of the bonnet. There must however be a sufficiently large deformation space below the bonnet for such a deformation process. In modern motor vehicles, the front bonnet is mostly a bonnet over the engine whereby the distance between it and the engine amounts to just a few centimeters. As a deformation path for the bonnet however, this spacing is insufficient for effective protection of the pedestrian. For this reason, devices have been developed for automatically raising the bonnet in the event of an impact, such devices increasing the distance between the bonnet and the engine therebelow and thus extending the deformation path available to the bonnet.
The position at which the head of a person who has been run over strikes the bonnet depends on his body size. Consequently, in order to protect children and adults to an equal extent, the entire surface of the bonnet must be raised.
Actuators for raising the bonnet of the most diverse type are known. It is likewise known for both a rear and a front edge of the bonnet to be raised by means of actuators. A motor vehicle in which the front edge of the bonnet is adapted to be raised in its entirety without a front actuator is described in DE 101 52 621 A1. An actuator operable on the rear edge of the bonnet moves it obliquely upwardly and to the rear in the event of an impact. Due to the movement to the rear, the front edge is also displaced and thereby raised in a guideway in the body which runs obliquely upwardly and to the rear. The disadvantage of this arrangement however is that due to the oblique guidance arrangement, the path which the bonnet has to traverse in order to attain a given distance from the engine is significantly longer than that for a vertical lift so that a comparatively rapid actuator having a large stroke is needed.
The bonnet should reach its raised position as quickly as possible following the detection of an impact; insofar as possible it should already be in the raised position when the pedestrian hits it. To this end, the bonnet must be accelerated rapidly and accordingly powerful actuators are needed. However, if they are only triggered when the pedestrian has already touched the bonnet, then he will be subjected to an additional blow due to the raising thereof. The protective effect of the raising process can thus turn into the very opposite thereof.